A cardiovascular and hormonal profile of hyper-responsivity in Type A and Type B subjects will be developed. Fifteen Type A and 15 Type B subjects will be selected using the Structured Interview. Following selection and a familiarization session the subjects will receive a graded exercise test and a mental arithmetic task on separate days. Several cardiovascular and hormonal variables will be assessed during exercise at different levels of work. Regression equations will be derived for each variable with Y as the predicted value e.g., heart rate, and oxygen consumption as the predictor. Each Y value can then be compared with the actual physiological value obtained during the psychological stressor (mental arithmetic). Differences between predicted and actual values will provide a physiological profile of hyper-responsiveness which will be used, in later studies, to assess the efficacy of various therapies to reduce hyper-responsivity. In addition, the profile will be used to address the question of mechanism by which these therapies act.